The role of oncologic resection and enucleation for small pancreatic neuroendocrine tumors

Solid Pseudopapillary Tumor of the Pancreas: Is Enucleation Safe?

BACKGROUND

While solid pseudopapillary tumor (SPT) of the pancreas are oncologically low-risk tumors, their resection with pancreaticoduodenectomy (PD) or partial pancreatectomy (PP) carries a significant risk for morbidity. To balance the favorable prognosis with the surgical morbidity of pancreas resection, this study explores the oncologic safety of enucleation (EN).

PATIENTS AND METHODS

The National Cancer Database (NCDB) was queried for resected SPT from January 2004 through December 2020. Perioperative outcomes and survival were analyzed with Kruskal-Wallis tests, and Kaplan-Meier analysis (with log-rank test). Survival analysis was performed to compare patients with and without lymph node (LN) metastases and binary logistic regression for predictors of LN metastasis.

RESULTS

A total of 922 patients met inclusion criteria; 18 patients (2%) underwent EN, 550 (59.6%) underwent PP, and 354 (38.4%) underwent PD. Mean tumor size was 57.6 mm. Length of hospital stay was significantly shorter for EN compared with PP and PD groups (3.8 versus 6.2 versus 9.4 days, p < 0.001). There was a nonsignificant improvement in unplanned readmission [0% versus 8% versus 10.7% (p = 0.163)], 30-day mortality [0% versus 0.5% versus 0% (p = 0.359)], and 90-day mortality [0% versus 0.5% versus 0% (p = 0.363)] between EN, PP, and PD groups. Survival analyses showed no difference in OS when comparing EN versus PP (p = 0.443), and EN versus PD (p = 0317). Patients with LN metastases (p < 0.001) fared worse, and lymphovascular invasion, higher T category (T3-4) and M1 status were found as predictors for LN metastasis.

CONCLUSIONS

EN may be considered for select patients leading to favorable outcomes. Because survival was worse in the rare cohort of patients with LN metastases, the predictors for LN metastasis identified here may aid in stratifying patients to EN versus resection.

Lymph node metastases and recurrence in pancreatic neuroendocrine neoplasms

BACKGROUND

The impact of lymph node metastasis on survival in pancreatic neuroendocrine neoplasms as well as their best surgical treatment is controversial. We aimed to determine the frequency and prognostic impact of lymph node involvement in pancreatic neuroendocrine neoplasms.

METHODS

Patients undergoing pancreatic resections for pancreatic neuroendocrine neoplasms between 2001 and 2019 were retrospectively analyzed based on a prospective database. Clinicopathological parameters and perioperative outcome were assessed. Overall and disease-free survival was analyzed. Subgroup analysis was performed for sporadic, nonfunctional pancreatic neuroendocrine neoplasms without distant metastases and ≥4 analyzed lymph nodes.

RESULTS

Of 605 surgically resected pancreatic neuroendocrine neoplasms, 55% were G1, 36% were G2, and 9% were G3 differentiated. At the time of resection, 34% of patients had lymph node metastasis, and 16% had distant metastases. For subgroup analysis, 314 patients were analyzed. Lymph node metastases occurred in 36% of patients and were most frequent in G3 patients (67%). An increase in tumor size and advancement was associated with higher rates of lymph node metastasis, and disease-free survival was significantly impaired. Significant differences in disease-free survival were observed between 1 and 3 (5-year disease-free survival 52%) and ≥4 positive lymph nodes (5-year disease-free survival 28%), as well as when G3 tumors were excluded. In multivariable analysis, grading, tumor stage, and especially lymph node metastases as well as the proposed pN1 and pN2 categories were confirmed as independent predictors of recurrence.

CONCLUSION

The presence and extent of lymph node involvement has considerable prognostic impact in pancreatic neuroendocrine neoplasms. This study, for the first time, validated the proposed pN2 stage for well-differentiated pancreatic neuroendocrine neoplasms.

Evaluation of Risk Factors for Distant and Lymph Node Metastasis of Pancreatic Neuroendocrine Tumors

Purpose

Metastases of pancreatic neuroendocrine tumors (pNETs) can be found at the time of diagnosis in 20–50% of cases. Small asymptomatic tumors may be left for observation; however, they can metastasize. The aim of the study was to evaluate risk factors for distant and lymph node metastases of pNETs.

Patients and methods

One hundred and fourteen patients with postoperatively confirmed pNET were analyzed retrospectively in a single ENETS Center of Excellence. The relationship between location, size, differentiation of the tumor, and occurrence of lymph node and distant metastases was analyzed.

Results

pNETs’ location was pancreatic head – 38 (33.3%), body or tail – 68 (59.7%), and 8 (7.0%) involved the entire organ. Fifty-six (49.1%) tumors were graded G1, 50 (43.9%) G2, and 8 (7.0%) G3. Seventy-two (63.2%) tumors were ≥2 cm in diameter, and 42 (36.8%) <2 cm. Twenty-two (19.3%) patients had distant metastases and 47 (41.2%) had lymph node metastases. In ≥2 cm tumors distant and lymph node metastases were more frequent (p < 0.05). Distant metastases incidence was significantly higher in distally located tumors (p = 0.01) and in G2 and G3 tumors (p < 0.01). In 9.5% of <2cm tumors, distant metastases were present at diagnosis.

Conclusion

Distant metastases are more often found in larger, distally located pNETs grade G2 and G3, while a higher occurrence of lymph node metastases seems to be associated only with larger tumor size. A considerable number of tumors <2 cm in size have distant metastases already at the diagnosis, which might indicate the need for careful qualification of smaller lesions for observation.

Comparison of Outcomes of Enucleation vs. Standard Surgical Resection for Pancreatic Neoplasms: A Systematic Review and Meta-Analysis

Background

With advancement in health technology, the detection rate of pancreatic neoplasms is increasing. Tissue sparing surgery (enucleation) as well as standard surgical resection are two commonly used modalities of management. There are studies comparing clinical outcomes between these two modalities; however, there is lack of studies that systematically pool the available findings to present conclusive and reliable evidence.

Methods

A systematic search was conducted using the PubMed, Scopus, and Google Scholar databases. Studies that were randomised controlled trials or cohort based or analysed retrospective data were considered for inclusion. Studies should have been done in adult patients with pancreatic neoplasms and should have examined the outcomes of interest by the two management modalities i.e., enucleation and standard surgical resection. Statistical analysis was performed using STATA software.

Results

A total of 20 studies were included in the meta-analysis. The operation time (in minutes) (WMD −78.20; 95% CI: −89.47, −66.93) and blood loss (in ml) (WMD −204.30; 95% CI: −281.70, −126.90) for enucleation was significantly lesser than standard surgical resection. The risk of endocrine (RR 0.32; 95% CI: 0.18, 0.56) and exocrine insufficiency (RR 0.16; 95% CI: 0.07, 0.34) was lower whereas the risk of post-operative pancreatic fistula (RR 1.46; 95% CI: 1.22, 1.75) was higher in enucleation, compared to standard surgical resection group. There were no differences in the risk of reoperation, readmission, recurrence, mortality within 90 days and 5-years overall mortality between the two groups.

Conclusions

Enucleation, compared to standard surgical resection, was associated with better clinical outcomes and therefore, might be considered for selected pancreatic neoplasms. There is a need for randomised controlled trials to document the efficacy of these two management techniques.

Prognostic Factors of Small Non-Functional Pancreatic Neuroendocrine Tumors and the Risk of Lymph Node Metastasis: A Population-Level Study

BACKGROUND

Small non-functional neuroendocrine tumors (NF-PNETs) are a heterogeneous subset of tumors with controversy regarding their optimal management. We aimed to analyze the prognostic factors of patients with small NF-PNETs and create a risk score for lymph node metastasis (LNM).

METHODS

Data of 751 patients with NF-PNETs ≤ 2 cm were obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Multivariate survival analysis was performed to analyze the prognostic factors. Logistic regression was used to identify risk factors for LNM.

RESULTS

Of the 751 patients, 99 (13.2%) were confirmed to have LNM. In multivariate survival analysis, LNM (hazard ratio [HR], 2.12; 95% CI, 1.04-4.32, p = 0.040) was independently associated with disease-specific survival. Logistic regression identified that tumor location in the head of the pancreas (odds ratio [OR], 4.33; 95% CI, 2.75-6.81; p < 0.001), size ≥ 1.5-2 cm (OR, 1.84; 95% CI, 1.17-2.87; p = 0.009), and grade III-IV (OR, 7.90; 95% CI, 1.79-34.90; p = 0.006) were independent risk factors of LNM. According to the OR value, the risk of LNM was scored as follows: a score of 1 for tumors located in the body/tail of the pancreas and 4 for those located in the head; a score of 1 for tumors <1 cm and 2 for those ≥1.5-2 cm; and a score of 1 for tumors with grade I-II and 8 for those with grade III-IV. Finally, the median score for this cohort was 4, with an interquartile range of 3-6. Therefore, patients were classified as three groups based on the risk score system: a total score of 1-3 for low risk, 4-6 for intermediate risk (OR, 2.98; 95% CI, 1.59-5.60; p = 0.001), and 7-14 for high risk (OR, 8.94; 95% CI, 4.50-17.7; p < 0.001), with an incidence of LNM 5.0%, 13.5%, and 31.8%, respectively (p < 0.001).

CONCLUSION

Surgical resection with regional lymphadenectomy is recommended for small NF-PNETs with malignant potential of LNM. A risk score for LNM based on tumor grade, location, and size may preoperatively predict LNM of small NF-PNETs and guide clinical practice.

Progress in the Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are a heterogeneous and orphan group of neoplasms that vary in their histology, clinical features, prognosis, and management. The treatment of PNETs is highly dependent on the stage at presentation, tumor grade and differentiation, presence of symptoms from hormonal overproduction or from local growth, tumor burden, and rate of progression. The US Food and Drug Administration has recently approved many novel treatments, which have altered decision making and positively impacted the care and prognosis of these patients. In this review, we focus on the significant progress made in the management of PNETs over the past decade, as well as the active areas of research. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.